Efeitos do modo ventilatório sobre variáveis hemogasométricas em equinos submetidos à mudança de decúbito durante a anestesia geral inalatória com halotano / Effects of the ventilatory regimen on arterial blood gas variables in horses that underwent a change in body position during halothane anesthesia

Compararam-se os efeitos da ventilação espontânea (V E) e controlada (V C) em equinos submetidos à mudança de decúbito durante anestesia. Dezesseis animais foram equitativamente divididos em dois grupos: V E e V C. Os procedimentos cirúrgicos foram iniciados com os animais em decúbito lateral esquerdo (DLE) e, após 75 minutos, os animais foram reposicionados em decúbito lateral direito (DLD). Análises hemogasométricas do sangue arterial foram realizadas após 30 e 75 minutos com os animais posicionados em cada decúbito (M1 e M2 no DLE e M3 e M4 no DLD, respectivamente). Durante a V E, observaram-se hipercapnia (PaCO2 >45mmHg), acidose respiratória (pH <7,35), redução significativa da oxigenação sanguínea após 75min da mudança de decúbito (M4: 205,8±124,7mmHg) em relação aos valores de PaO2 observados antes da mudança de posicionamento (M1: 271,8±84,8mmHg). A Vc foi associada a valores de PaCO2 e pH mais próximos da normalidade bem como resultou em valores de PaO2 significativamente maiores (52 a 96 por cento de elevação nos valores médios) que a V E. Conclui-se que a mudança de decúbito, em equinos anestesiados com halotano e mantidos sob V E, resulta em hipercapnia, acidose respiratória e diminuição dos valores de PaO2. A instituição de V C, desde o início da anestesia, previne a acidose respiratória, além de resultar em valores de PaO2 mais próximos do ideal para animais respirando O2 a 100 por cento.

The effects of spontaneous (SV) and controlled ventilation (CV) were compared in horses undergoing changes in body position during anesthesia. Sixteen animals were equally distributed in two groups: SV and CV. All surgical procedures were commenced on left lateral recumbency (LLR) and 75 minutes later the animals were repositioned on right lateral recumbency (RLR). Arterial blood gas analyses were performed at 30 and 75 minutes after each recumbency (M1 and M2 for LLR and M3 and M4 for RLR). Hypercapnia (PaCO2 >45mmHg), respiratory acidosis (pH <7.35), and significant decrease in PaO2 after 75min of change in body position (M4: 205.8±124.7mmHg) in comparison to PaO2 values before the change of position (M1: 271.8±84.8mmHg) were observed during SV. When compared to the SV group, CV resulted in significantly higher PaO2 levels (52 to 96 percent increase). It was concluded that the change in the body position in spontaneously ventilating halothane-anesthetized horses causes impairment in arterial oxygenation. The use of CV since the beginning of anesthesia prevents the respiratory acidosis and maintains arterial oxygen levels that are closer to values expected during the use of 100 percent O2.

Efeitos da metadona ou do neostigmine, associados à lidocaína administrados pela via epidural em cães / Effects of methadone or neostigmine in combination with lidocaine for epidural anesthesia in dogs

Seis cães adultos, de raças e sexos variados, com peso de 13,3±3,4kg (média±DP), foram utilizados no estudo. Os animais foram tranqüilizados com acepromazina (0,1mg/kg, IV) e, após 30 minutos, foram aleatoriamente submetidos à anestesia epidural com um dos seguintes tratamentos: lidocaína 2 por cento 0,25ml/kg (controle); neostigmine 0,01mg/kg+lidocaína (NEO); metadona 0,3mg/kg+lidocaína (MET). Todos os animais foram submetidos aos três tratamentos com intervalo mínimo de uma semana. Foram mensuradas as freqüências cardíaca (FC) e respiratória (FR), a pressão arterial sistólica (PAS), o tempo para a perda do reflexo interdigital, a duração e a altura do bloqueio sensitivo, durante um período de 90 minutos. Não houve diferença significativa entre os tratamentos nos valores de FC, PAS e FR, bem como na duração do bloqueio sensitivo e no tempo para a perda do reflexo interdigital. No grupo MET, houve diminuição de FC dos 30 aos 90 minutos em relação ao valor basal. Bloqueio sensitivo mais cranial também foi observado em MET. A associação de neostigmine ou metadona não prolongou o período hábil de anestesia epidural produzido pela lidocaína em cães. A metadona, mas não o neostigmine, parece estender mais cranialmente o bloqueio epidural pela lidocaína.

Six mature mongrel dogs of both genders, weighing 13.3±3.4kg (mean±SD) were used in the present research. Thirty minutes after premedication with intravenous acepromazine (0.1mg/kg, IV), dogs were randomly assigned to receive epidural administration of one of following three treatments: 2 percent lidocaine 0.25ml/kg (control), or neostigmine 0.01mg/kg plus lidocaine (NEO), or methadone 0.3mg/kg plus lidocaine (MET). All dogs received all treatments in a cross-over design with at least one-week interval. Heart rate (HR), respiratory rate (RR), systolic arterial pressure (SAP), time to loss of pedal withdrawal reflex, duration of epidural anesthesia, and cranial spread of epidural anesthesia were evaluated for 90 minutes. No differences among treatments in HR, RR, SAP, duration of anesthesia, and time to loss of pedal withdrawal reflex were found. In MET, HR decreased from 30 to 90 minutes compared to baseline and there was a higher cranial spread of epidural anesthesia than in controls and NEO animals. Neostigmine or methadone did not prolong epidural anesthesia with lidocaine in dogs. Methadone, but not neostigmine, appeared to result in more cranial spread of epidural anesthesia with lidocaine.

Sedative and cardiorespiratory effects of acepromazine or atropine given before dexmedetomidine in dogs.

To test the hypothesis that acepromazine could potentiate the sedative actions and attenuate the pressor response induced by dexmedetomidine, the effects of acepromazine or atropine were compared in six healthy adult dogs treated with this alpha2-agonist. In a randomised block design, the dogs received intravenous doses of either physiological saline, 0.05 mg/kg acepromazine or 0.04 mg/kg atropine, 15 minutes before an intravenous dose of 5 microg/kg dexmedetomidine. The dogs' heart rate was reduced by 50 to 63 per cent from baseline and their mean arterial blood pressure was increased transiently from baseline for 20 minutes after the dexmedetomidine. Atropine prevented the alpha2-agonist-induced bradycardia and increased the severity and duration of the hypertension, but acepromazine did not substantially modify the cardiovascular effects of the alpha2-agonist, except for a slight reduction in the magnitude and duration of its pressor effects. The dexmedetomidine induced moderate to intense sedation in all the treatments, but the dogs' sedation scores did not differ among treatments. The combination of acepromazine with dexmedetomidine had no obvious advantages in comparison with dexmedetomidine alone, but the administration of atropine before dexmedetomidine is contraindicated because of a severe hypertensive response.

Cryopreservation effects on domestic cat epididymal versus electroejaculated spermatozoa.

Frozen-thawed epididymal spermatozoa have already been successfully used in artificial insemination in the domestic cat, proving to be a valuable resource for the reproduction of felid species, which are threatened with extinction. The aim of this study was to compare the effects of freezing and thawing on domestic cat semen collected by electroejaculation (EL) and from the epididymides (EP) and vasa deferentia. Ten adult cats were anesthetized, electroejaculated and immediately thereafter, orchiectomized. Epididymal spermatozoa were collected through the compression of caudae epididymidis and vasa deferentia. Spermatozoa were frozen-thawed following a single protocol. Sperm motility, sperm progressive status (0-5), plasma membrane integrity and morphology (light and transmission electron microscope) were assessed on two occasions, immediately after collection and after freezing and thawing. There were no significant differences between the electroejaculated and epididymal fresh or frozen-thawed spermatozoa for any of the variables. However, the incidence of acrosome defects after freezing and thawing increased by 19% based on light microscopy, whereas ultrastructural images revealed acrosome damages in most sperm cells. Since these acrosomal changes are known to affect sperm fertilising capacity, further studies are needed to optimize cryopreservation techniques for epididymal as well as electroejaculated domestic cat spermatozoa.

Efeitos cardiorrespiratório e analgésico da clonidina, xilazina, butorfanol, buprenorfina e tramadol, associados a lidocaína, da anestesia epidural de cães

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